Specimens of endometrial carcinoma will be used for in vitro studies involving organotypic cultures of tissue fragments, separation of glands from stromal elements, and cultures of monolayers of epithelial and stromal cells. Levels of enzymatic activities (e.g., 17-beta-hydroxysteroid dehydrogenase) and concentrations of estradiol and progesterone receptors will be measured in order to evaluate conditions necessary for the preservation and augmentation of these levels. Increment in 17-beta-dehydrogenase activity are a rather specific indicator of response of the tissue to progestins. Correlations between receptor levels, 17-beta-dehydrogenase activity, and in vitro responsiveness to progestins will be sought. In some cases, patients with endometrial carcinoma will receive medroxyprogesterone acetate for a few days in order to evaluate, morphologically and biochemically, in vivo effects of the progestin and compare them with results obtained in vitro with pretreatment specimens. Epithelial cells derived from the same specimens will be transplanted into hamsters and nude mice subjected to hormonal manipulations. Other studies to be conducted on specimens of endometrial cancer include the measurement and characterization of the newly identified "available" estrogen receptors in the endometrial nuclei, the assessment of hormonal influences on rates of pyrimidine synthesis, and quantitation of the uptake and metabolism of estrogens, androgens and progesterone, by superfusion of cell suspensions.